Check Valves

by Jeff
(Trenton, NJ)

I have an older SpeedAire portable compressor and I believe that my problem is the check valve. I have already replaced the pressure switch and integral unloader valve but it will still run up to pressure and then bleed off all the compressed air once the motor stops. If I don't turn the unit off quickly, when it attempts to restart it will blow the breaker.

Based on the information on your site, I now believe that the original pressure switch and unloader were fine and that the problem is the check valve. Unfortunately I haven't been able to locate your information on check valves - where they are usually located, steps for diagnosing and either repairing or replacing them.

Bill says...

Yes Jeff, it does sound like your check valve is allowing tank pressure to flow back out to atmosphere when your compressor stops.

The check valve in question is commonly located where the compressed air line from the compressor head enters the tank. It passes through an integral check valve there.

Pull the power cord, dump all the air in the tank, and disassemble this connection. The check valve should only pass air in one direction, and if you blow in it, and air flows both ways, then the check valve has failed.

Try cleaning the seats first, and if that doesn't work, change it out.

Cheers,

Bill